An advisory panel for the FDA voted 11-1 in favor of decongestants containing 10 milligrams of the ingredient phenylephrine as effective drugs. The panel meeting, held in Silver Spring, Md., was in response to a petition from researchers who believe that phenylephine is ineffective when taken orally, particularly at its currently approved dosage.

Johnson & Johnson and Wyeth used to sell over-the-counter decongestants containing the ingredient pseudoephedrine. But, because this compound is also used to make the illegal and dangerous drug known as crystal methamphetamine, retailers such as Wal-Mart (WMT, Fortune 500), Target (TGT, Fortune 500) and Albertsons have moved these products behind-the-counter. Patients must now interact with pharmacists and show identification to buy pseudoephedrine products.

Johnson & Johnson and Wyeth continue to sell pseudoephedrine products. But in order to continue selling decongestants over the counter, these companies reformulated their pills to contain phenylephrine.

"We think it's effective, if used as directed," said Wyeth spokesman Doug Petkes, prior to the vote.

But Schering-Plough (SGP, Fortune 500) did not reformulate its pseudoephedrine product, Claritin-D, which it now sells behind the counter. The company's stock dipped more than 2 percent throughout the day, ahead of the vote.

Leslie Hendeles and Randy Hatton, both pharmacy professors from the University of Florida in Gainesville, believe that phenylephrine is a poor substitute for pseudoephedrine. They petitioned the FDA to hold a meeting about the effectiveness of phenylephrine.

"We're seriously concerned that a 10 milligram does of this drug is ineffective," said Paul Doering, pharmacy professor at the University of Florida and a co-director with Hatton at the Drug Information and Pharmacy Resource Center, in an interview prior to the vote.

Doering, who is not a petitioner, said the issue is much bigger than a matter of dosage. He said an analysis conducted by his University of Florida colleagues indicated the evidence about phenylephrine effectiveness "is meager indeed."

Analysts said the issue isn't likely to have a major impact on drug companies, which rely more heavily on individual prescription drugs for sales, than individual over-the-counter drugs.

For example, out of Wyeth's $8.7 billion sales total for the first nine months of 2007, only $110 million came from Robitussin. Some, but not all, of the Robitussin varieties contain phenylephrine.

Wyeth's Advil Cold & Sinus contains pseudoephedrine, and sales totaled $20 million during the same time period.

"From an analytic point of view, it's really not all that material," said Les Funtleyder, analyst for Miller Tabak. But he said it represents a trend in "the growing consumerism of healthcare," in which patients are expected to make decisions for themselves and are allowed greater access to products and information.

Funtleyder does not own stock in the companies mentioned here and Miller Tabak does not conduct business with them.